1. Field of the invention
This invention relates to the field of water purification units, in particular, portable water filtration pumps for back-country or travel use and other applications where manual water purification is required.
2. Statement of the problem
Water purification is a critical problem in today's world. While presently there are a large number of systems available for home and industrial purification, a strong need exists for a portable system of water purification, particularly for a lightweight, compact water filtration unit. Such a unit is necessary for purifying water sources for travelers, campers, backpackers, fishermen, hunters, rafters, in emergency situations, and the like.
Water sources, even those that appear to be clear, are often contaminated. Water contaminants include particulate matter, chemicals, insects, nematodes, fungi, algae, yeasts, microorganisms, discoloration and radioactive contamination. The microorganisms often found in water sources include pathogenic microbes such as protozoa (which includes Giardia Lamblia), bacteria and viruses. Chemicals often found in water sources include chlorine, herbicides, and pesticides.
Present portable systems for water filtration are of three types: boiling, chemical treatment, and mechanical filtration. Boiling water is time consuming and requires the need for fire. Also, boiling water will only kill microorganisms. It does not remove the contaminants. Chemical treatments, such as iodine tablets, leave an aftertaste, and may produce an allergic reaction with some people. Also, chemical treatments will only kill microorganisms and do not remove contaminants.
Only mechanical filtration units remove the contaminants from the water. Typically, mechanical filtration units are of two types, passive filtration units and pump filtration units.
Passive filtration systems typically use a water bag having a filtration system in the bottom of the bag. Water is poured into the bag which is then hung onto a tree or elevated structure. Water flows downward due to the force of gravity through the filters in the bag and into a reservoir. This type of system is cumbersome to transport, operates slowly and requires frequent replacement of the filters due to bacteria growth in the filters.
There are presently several pump-type water purifiers available on the market. One such device is the FIRST NEED WATER PURIFIER, available from General Ecology, Inc. 151 Sherree Blvd, Lionville, Pa. This purifier uses a handle to move a pump piston vertically in a cylinder. A canister containing a charcoal filter is mounted parallel to the cylinder and is connected by plastic tubing to the cylinder. The bottom of the cylinder has another piece of tubing which is placed in the water source. The bottom of the canister has a short piece of tubing which is placed in the water container. Operation of the handle pumps water through the canister to filter the water. This system weighs approximately sixteen ounces and requires frequent sterilization of the filter by chlorine to prevent bacteria growth. The canister requires replacement at periodic intervals. The replacement canisters are relatively expensive. This system under normal usage purifies water at the rate of one quart per ninety seconds. A prefilter is recommended for use with this system.
Another popular portable water purification filter is manufactured by Katadyn. This system uses a ceramic filter. It also uses a handle type pump to move water through the system. This system is expensive compared with other devices.
A third commercially available water filter pump is the MSR WATERWORKS FILTER, manufactured by Mountain Safety Research, Seattle, Wash. This system uses a small, horizontally-mounted pump with a lever handle to pump water through an articulated urethane foam prefilter, fine mesh stainless steel screen, a cylinder of activated carbon and a micro-porous membrane cartridge having a pore size ratio of 0.1 micron absolute. This system screws on to a water container. This system is relatively expensive with expensive replacement filters. The approximate weight of this system is 20 ounces. Other devices are known that using a separate pump and filter mechanism. These devices are cumbersome to operate and are relatively slow to filter water.
There presently exists a need for a lightweight, compact, inexpensive water purification pump that operates with uniform flows at high rates with extensive exertion.